Everything rendered in black except sky background in cycles
Welcome!
In future questions, please try to provide as much detail as possible, optimally with screenshots to explain the question or issue.

Specifically here, it appears you added an overriding faulty material (Material.002) that replaces all other materials in your scene.

To fix the issue, remove it by going to the Scene Tab in the Properties Window, scrolling down to the Layer property group, then clicking the delete ("X") button in the Material box.